1. Field of the Invention
The present invention relates to improvements in or to magnetic means for withdrawing magnetic gel beads from a biological medium.
2. Description of the Background
Magnetic gels useful for immunoenzymatic assays are known through French Patent of INSTITUT PASTEUR No. 2 334 106. These magnetic gels are constituted by an acylamide and/or agarose gel containing magnetic particles, coupled with a protein such as an antibody or an antigen, through a suitable coupling agent, such as glutaraldehyde. They are used for carrying out the immunoenzymatic assay of the antigen or of the corresponding antibody contained in a biological liquid to be assayed. After incubation, the magnetic gel is separated in a first step, from the biological liquid and, in the second step, from the protein (antigen or antibody) marked by an immunoenzymatic assay enzyme, each time by applying a magnetic field outside the tube in which the assay takes place, to retain the magnetic gel on the wall of the tube.
French Pat. No. 2,537,725 uses specific antigenic anti-determinant antibodies, for the immunobacteriological detection of pathogenic germs possessing specific antigenic determinants, in contaminated biological media. In accordance with the process of detection which forms the subject of this patent, after incubation with the biological liquid supposed contaminated, the magnetic gel beads are withdrawn from the biological liquid by magnetic means, preferably constituted by a magnetizable rod, by means of which they are transferred to a gelosed medium on which the detection process is pursued. The magnetizable rod used for this purpose is a magnetizable rod coated with "Teflon".
It has however become apparent that such a magnetizable rod has the drawback on the one hand of being insufficiently isolated by the "Teflon" coating and on the other hand of being liable to come into undesirable contact with naturally magnetic surfaces in the course of the transfer operation.